
    //函数的几种形式
    function add(a, b) {//C-style
        return a + b;
    }

    let sub = function (a, b) {//函数类型
        return a - b;
    };
    let x = 2;
    let y = 3;

    console.log(x + "+" + y + "=", add(x, y));
    console.log(x + "-" + y + "=", sub(x, y));
    console.log(x + "*" + y + "=", function (a, b) {//匿名函数
        return a * b;
    }(x, y));
